A method starting from furfural and goes through general formulae (II) and (III) has previously been known as the most efficient method of producing isocarbacyclin [Tetrahedron Letters, 25, 5087 (1984)]. ##STR3##
In the formulae, --OZ represents a t-butyldimethylsilyloxy group (same hereinafter).
According to this method, the step of deriving the triene compound of general formula (III) from the acetoxy compound of general formula (II) requires the use of 3-butenyllithium. Hence, it has the serious defect of using a very large amount of mercuric chloride for production of 3-butenyllithium. The present inventors studied a method of avoiding the use of mercury and further extensively worked in search of a method by which isocarbacyclin and its analogs can be synthesized in less process steps. These efforts have led to the discovery that isocarbacyclin and its analogs can be synthesized in less process steps by preparing the isocarbacyclin derivatives of general formula (I) and hydrolyzing them; and consequently, to the accomplishment of the present invention.